A Case of Chronic Conjunctivitis Caused by Fusobacterium nucleatum Misdiagnosed as Inclusion Conjunctivitis

Purpose: To report a case of chronic conjunctivitis caused by <i>Fusobacterium nucleatum</i> misdiagnosed as adult inclusion conjunctivitis.Case summary: A 48-year-old female visited our clinic complaining of conjunctival injection and discharge in her right eye that had started 9 months earlier. Slit lamp examination showed conjunctival exudates with follicular hypertrophy on the upper and lower palpebral conjunctiva of the right eye. Adult inclusion conjunctivitis was suspected, and polymerase chain reaction tests for 12 sexually transmitted infections, serum <i>Chlamydia trachomatis</i> antibody test, sputum tests, and urine tests were performed. The serum trachomatis IgM was negative, but IgG was positive; there were no other specific findings. The patient was treated with oral doxycycline and topical antibiotics eyedrops for 1 week, but there was no improvement. <i>Fusobacterium nucleatum</i> was detected in a conjunctival swab culture. The oral antibiotic was changed to amoxicillin/clavulanic acid. After 1 week, the symptoms improved and the chronic conjunctivitis and follicles decreased; 4 weeks later, recovery was complete.Conclusions: Chronic conjunctivitis caused by bacteria such as <i>Fusobacterium nucleatum</i> should be considered if adult inclusion conjunctivitis is suspected and does not respond to treatment.